1. Field of the Invention
The present invention relates to an optical (fiber) connector, for example, used in a multiplex transmission line of an automotive vehicle, a receptacle provided in the optical connector, and a manufacturing method for the receptacle.
2. Prior Art
There has been a generally known optical connector (disclosed in Japanese Utility Model Laid-open No. H. 6-33443) that was proposed by the same assignee of the present application. The optical connector has an optical fiber cable, an optical element module, and a sleeve provided therebetween. The optical element module is also called as a light-receiving/light-emitting optical module, a transmission module, an FOT (Fiber Optic Transceiver), or the like.
Referring to FIG. 27, there is shown the optical connector, in which denoted 201 is the sleeve and 202 the optical connector.
The sleeve 201 is mounted in a receptacle 203 (an instrument side connector) composing the optical connector 202. The receptacle 203 accommodates a pair of optical element modules 204, 204 (a light-emitting element module 204 and a light-receiving element module 204). There is also shown an optical plug (an optical fiber cable side connector) 205 provided with a pair of optical fiber cables 206, 206 (one of them is illustrated). The optical plug 205 is an optical connector mating with the receptacle 203 via the sleeve 201 that optically connects the optical element modules 204, 204 to the optical fiber cables 206, 206.
The optical connector 202 will be discussed in detail together with the sleeves 201, 201. The optical connector 202 has the receptacle 203 and the optical plug 205 mating with each other.
The receptacle 203, as illustrated in FIGS. 27 and 28, has a synthetic resin housing 207 including accommodation chambers 208, 208 in each of which an optical element module 204 made of an elastic material like a rubber is held by a back sheet 209. In a rear face of the housing 207, there is provided a cap 210 attached thereto. At the front of the accommodation chambers 208, 208 holding the optical element modules 204, 204, there is provided a pair of receiving cylinders 212, 212 each extending coaxialy with one of lenses 211, 211. The receiving cylinders 212, 212 each receive one of the sleeves 201, 201 inserted therein.
The sleeve 201 consists of a cylindrical holder 214 and an optical fiber cable 213 (a plastic, multi-mode optical fiber cable) bonded to the holder 214. The optical fiber cable 213 consists of a core and a cladding (not shown). The sleeve 201 has each end surface given an extremely precise grinding.
Meanwhile, the optical plug 205 mating with the receptacle 203, as illustrated in FIGS. 27 and 29, has a pair of ferrule assemblies 215, 215, a plug housing 217, a spring cap 218 engagedly secured to the plug housing 217, and a boot 219 engagedly secured to a rear portion of the spring cap 218. The ferrule assemblies 215, 215 cover the optical fiber cables 206, 206, each of which has an exposed leading end extending forward. The plug housing 217 has a cylindrical partition 216 for protecting the ferrule assemblies 215, 215 received therein.
The plug housing 217 also has shoulders 217a, 217a abutting against rim flanges 215a, 215a each outwardly formed on a rear half of the ferrule assembly 215. Between the flange 215a and an inner cylinder 218a of the spring cap 218, there is mounted a spring 220 for resiliently biasing forward the ferrule assembly 215.
When the flange 215a is abutting against the shoulder 217a (FIG. 29), a fore end portion a of the ferrule assembly 215 (corresponding to the position of a light receiving/emitting end surface of the optical fiber cable 206 as illustrated in FIG. 29) is not extending from a fore end b (FIG. 29) of the plug housing 217 to stay at a withdrawn position therein.
Referring to FIG. 27, the receptacle 203 and the optical plug 205 having such constitutions will be further discussed in electrical and optical connection thereof
On engagement of the receptacle 203 and the optical plug 205, the receiving cylinders 212, 212 enter the plug housing 217, and at the same time, the ferrule assemblies 215, 215 enter the receiving cylinders 212, 212. Each ferrule assembly 215 abuts against a leading end of the receiving cylinder 212 with an adequate contact pressure therebetween by the resiliency of the spring 220.
In this state, between the leading end a (FIG. 29) and the sleeve 201, there is only a minimum clearance (not shown), minimizing a clearance optical loss thereof.
Nevertheless, the aforementioned prior art has the housing 207 that accommodates the sleeves 201, 201 and the optical element modules 204, 204 inserted therein. This assembling work is very laborious and is not good in workability, resulted in a higher manufacturing cost.
Furthermore, the sleeve 201 and the optical element module 204 are defined separately from each other, which provides clearances therebetween. Such clearances cause another optical loss (clearance loss) in addition to the clearance loss between the leading end a (FIG. 29) and the sleeve 201. This may cause an adverse effect on an optical communication thereof.
Moreover, the receptacle 203 is completed after a plurality of steps each forming the housing 207, the optical element module 204, the sleeve 201, and the cap 210, together with steps for sequentially assembling these constitutions. The large number of steps cause a higher manufacturing cost.
In addition, the assembling step of the optical element module 204 includes a forming step of the lead pin (no reference numeral) having an optical element and a molding step of a body (no reference numeral) from a transparent resin for protecting the lead pin.